(1) Field of the Invention
The present invention relates to a reflecting mirror and more particularly to a multi-layered surface reflecting mirror superior in freedom from glare, visibility, decorative aspect, productivity, cost, etc. The multi-layered surface reflecting mirror of the present invention is used mainly as a rearview mirror for automobiles, a mirror with a convex surface that warns drivers against hazards on the road, an ornamental mirror, etc. and further has other wide applications.
(2) Description of the Prior Art
As an example of the multi-layered surface reflecting mirror, Japanese Patent Application Kokai (Laid-Open) No. 165805/1988 discloses a multi layered surface reflecting mirror comprising a glass substrate, a dielectric multi-layered film formed on one side of the substrate and a light-absorbing film formed on the back side of the substrate wherein the dielectric multi-layered film is constituted by laminating three to six (3 to 6) dielectric layers having alternately differing refractive indexes and at least one of the three to six dielectric layers has an optical thickness of .lambda./2.
FIG. 8 shows the spectral luminous efficiency V' (.lambda.) for dark adaptation of the human eye [curve (1)] the spectral energy characteristic P (.lambda.) of an automobile headlight (halogen lamp) [straight line (2)] and their product P (.lambda.).times.V'(.lambda.) [curve (3)]. As is clear from FIG. 8, the wavelength portion sensible by the human eye, of a light emitted at night from the headlight (halogen lamp) of an automobile running behind, lies mainly in a wavelength region of 480-550 nm. Accordingly, in order for a reflecting mirror to have a glareless property, it is necessary that the mirror have a low reflectance at said wavelength region.
The multi-layered surface reflecting mirror disclosed in said patent document has a low reflectance at a wavelength region of 480-580 nm and accordingly has an excellent glareless property, as understood from its spectral reflection characteristic shown in FIG. 9. This reflecting mirror has a low reflectance in the wavelength region where the glareless property is required and a high reflectance in other wavelength regions; therefore, the reflecting mirror has excellent visibility, too.
In the multi-layered surface reflecting mirror disclosed in said patent document, however, a number of (three to six) dielectric layers are provided on one side of a glass substrate for the formation of a dielectric multi-layered film, thus making complex the vapor deposition step required for the formation of said film; moreover, it is necessary to form a light-absorbing film on the other side of the substrate by coating and baking, in a step separate from said deposition step, thus inviting low productivity and a high cost.